There appears to be a few Raleigh and Peugeot bikes from mid 90s on Ebay
Not based on scientific, but a lot of the "retro" racers of that vintage are built out of scaffolding tubes.
I've got an '87 (Raleigh) and a '97 (Dawes) 531 frame. The Raleigh required a strip and spray (others disagree, but if it's your bike, you're in charge of the cosmetics!) but the Dawes was ex-display and as good as out the box. I also liked the dark prussian blue it came in.
With the Dawes I just winged it and assumed that as it was reasonably new that "modern" components would fit and fortunately they did. It has a 105 external cup bottom bracket, managed to convert to STI shifters by getting the correct stops ordered for the downtube brazeons, ordered a smaller band clamp for holding on front derailleur. Also got 105 brake calipers on it that give sufficient clearance for 25 tyres and full mudguards. That it came with the headset installed and the steerer cut to correct height also helped. Seat post clearance was very tight (there's a thread about it!) but a bit of spreading it with an old post and then lots of grease and twisting / spinning it in with my weight pushing down on it cured that.
The Raleigh I tried the same approach but was hamstrung by head tube being of a weird diameter and the steerer having been cut too short previously. That ended up requiring some custom metalwork shimming and steerer extension to rectify (but because it were steel, it were possible once I'd found a man who knew what he was doing!). The BB was regular "English" threaded so had the shop put a modern one in there. I got away with modern brake calipers too and same tyre and mudguard combo as the Dawes, but the blocks are at the limit of their range.
So you can take the measure everything precisely, then again, and again approach. Or you can take the "it'll all be fine and if not I can shim / shove it in and it will fit" approach. Both seem to work!
But definitely do it! It's great fun, I learned a lot about bikes and bike maintenance, had a good excuse to buy all sorts of tools I'd otherwise never need and will be building my own TT bike after accumulating all the remaining bits.
Also, remember and keep a spreadsheet of what you've spent / how much you've saved by buying in the sale / second hand and then do a grand total at the end to demonstrate to your bank manager / purse-string owner how much you saved and how much you can spend on your next project!